1. Field of the Invention
The invention relates to computer user interfaces. More particularly, the invention concerns a portable computing device that receives user input including a sequence of handwritten strokes entered on top of each other.
2. Description of the Related Art
Handheld digital devices are becoming increasingly widespread. Some digital devices are dedicated to simpler tasks, as in the case of a television remote control. Other devices offer general purpose computing platforms, as in the case of personal data assistants (PDAs). Other devices offer a combination of these, as in the case of many mobile phones, which place and receive calls, but also perform address management, web surfing, text messaging, and other computing functions.
Although some handheld, general purpose computers offer a full keyboard, many others do not. Some handheld computers offer handwriting recognition, which helps avoid some of the problems of not having a full keyboard. However, the display of a portable computing device is reduced in size, compared to a normal computer display. And, since handwriting entry occurs on the display, then the handwriting entry area is effectively reduced with respect to a full sized computer. Being constrained with a reduced handwriting entry area presents various challenges in designing user interfaces that are still simple, intuitive, fast, and powerful.